Get crystal-clear views inside your aquarium without any distortion. Acrylic viewer box minimizes light reflection for improved surface viewing (as opposed to frontal viewing). Also makes the ideal tool for aquascaping or taking detailed photographs of your specimens from a bird's eye view. Also good for viewing tidepools. Made with a clear bottom and black sides. Required aquarium opening size to use the viewer is 8-1/4" x 8-1/4".